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Shulyak VA, Morozov NS, Gracheva AV, Gritskevich MD, Chebotarev SN, Avdeev VV. Anisotropy of Electrical and Thermal Conductivity in High-Density Graphite Foils. NANOMATERIALS (BASEL, SWITZERLAND) 2024; 14:1162. [PMID: 38998767 PMCID: PMC11243072 DOI: 10.3390/nano14131162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2024] [Revised: 06/30/2024] [Accepted: 07/05/2024] [Indexed: 07/14/2024]
Abstract
Flexible graphite foils with varying thicknesses (S = 282 ± 5 μm, M = 494 ± 7 μm, L = 746 ± 8 μm) and an initial density of 0.70 g/cm3 were obtained using the nitrate method. The specific electrical and thermal conductivity of these foils were investigated. As the density increased from 0.70 g/cm3 to 1.75 g/cm3, the specific electrical conductivity increased from 69 to 192 kS/m and the thermal conductivity increased from 109 to 326 W/(m·K) due to the rolling of graphite foils. The study showed that conductivity and anisotropy depend on the shape, orientation, and contact area of thermally expanded graphite (TEG) mesoparticles (mesostructural factor), and the crystal structure of nanocrystallites (nanostructural factor). A proposed mesostructural model explained these increases, with denser foils showing elongated, narrowed TEG particles and larger contact areas, confirmed by electron microscopy results. For graphite foils 200 and 750 μm thick, increased density led to a larger coherent scattering region, likely due to the rotation of graphite mesoparticles under mechanical action, while thinner foils (<200 μm) with densities > 1.7 g/cm3 showed increased plastic deformation, indicated by a sharp reduction in the coherent scattering region size. This was also evident from the decrease in misorientation angles with increasing density. Rolling reduced nanocrystallite misorientation angles along the rolling direction compared to the transverse direction (TD) (for 1.75 g/cm3 density ΔMA = 1.2° (S), 2.6° (M), and 2.4° (L)), explaining the observed anisotropy in the electrical and mechanical properties of the rolled graphite foils. X-ray analysis confirmed the preferred nanocrystallite orientation and anisotropy coefficients (A) using Kearns parameters, which aligned well with experimental measurements (for L series foils calculated as: A0.70 = 1.05, A1.30 = 1.10, and A1.75 = 1.16). These calculated values corresponded well with the experimental measurements of specific electrical conductivity, where the anisotropy coefficient changed from 1.00 to 1.16 and mechanical properties varied from 0.98 to 1.13.
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Affiliation(s)
- Vladimir A Shulyak
- Department of Chemistry, Lomonosov Moscow State University, Moscow 119991, Russia
| | - Nikolai S Morozov
- Department of Chemistry, Lomonosov Moscow State University, Moscow 119991, Russia
| | - Alexandra V Gracheva
- Department of Chemistry, Lomonosov Moscow State University, Moscow 119991, Russia
| | - Maria D Gritskevich
- Department of Chemistry, Lomonosov Moscow State University, Moscow 119991, Russia
| | - Sergei N Chebotarev
- Department of Chemistry, Lomonosov Moscow State University, Moscow 119991, Russia
| | - Viktor V Avdeev
- Department of Chemistry, Lomonosov Moscow State University, Moscow 119991, Russia
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Plenča K, Cvetnić S, Prskalo H, Kovačić M, Cvetnić M, Kušić H, Matusinović Z, Kraljić Roković M, Genorio B, Lavrenčič Štangar U, Lončarić Božić A. Biomass Pyrolysis-Derived Biochar: A Versatile Precursor for Graphene Synthesis. MATERIALS (BASEL, SWITZERLAND) 2023; 16:7658. [PMID: 38138800 PMCID: PMC10744795 DOI: 10.3390/ma16247658] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 12/05/2023] [Accepted: 12/13/2023] [Indexed: 12/24/2023]
Abstract
Graphene, a two-dimensional carbon allotrope with a honeycomb structure, has emerged as a material of immense interest in diverse scientific and technical domains. It is mainly produced from graphite by mechanical, chemical and electrochemical exfoliation. As renewable energy and source utilization increase, including bioenergy from forest and woody residues, processed, among other methods, by pyrolysis treatment, it can be expected that biochar production will increase too. Thus, its useful applications, particularly in obtaining high-added-value products, need to be fully explored. This study aims at presenting a comprehensive analysis derived from experimental data, offering insights into the potential of biomass pyrolysis-derived biochar as a versatile precursor for the controlled synthesis of graphene and its derivatives. This approach comprehended the highest energy output and lowest negative environmental footprint, including the minimization of both toxic gas emissions during processing and heavy metals' presence in the feedstock, toward obtaining biochar suitable to be modified, employing the Hummers and intercalation with persulfate salts methods, aiming at deriving graphene-like materials. Material characterization has revealed that besides morphology and structural features of the original wooden biomass, graphitized structures are present as well, which is proven clearly by Raman and XPS analyses. Electrochemical tests revealed higher conductivity in modified samples, implying their graphene-like nature.
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Affiliation(s)
- Karla Plenča
- Faculty of Chemical Engineering and Technology, University of Zagreb, Marulićev trg 19, 10000 Zagreb, Croatia; (K.P.); (M.K.); (M.C.); (M.K.R.)
| | - Sara Cvetnić
- Department for Safety and Protection Engineering, Karlovac University of Applied Sciences, Trg J.J. Strossmayera 9, 47000 Karlovac, Croatia; (S.C.); (H.P.); (Z.M.)
| | - Helena Prskalo
- Department for Safety and Protection Engineering, Karlovac University of Applied Sciences, Trg J.J. Strossmayera 9, 47000 Karlovac, Croatia; (S.C.); (H.P.); (Z.M.)
| | - Marin Kovačić
- Faculty of Chemical Engineering and Technology, University of Zagreb, Marulićev trg 19, 10000 Zagreb, Croatia; (K.P.); (M.K.); (M.C.); (M.K.R.)
| | - Matija Cvetnić
- Faculty of Chemical Engineering and Technology, University of Zagreb, Marulićev trg 19, 10000 Zagreb, Croatia; (K.P.); (M.K.); (M.C.); (M.K.R.)
| | - Hrvoje Kušić
- Faculty of Chemical Engineering and Technology, University of Zagreb, Marulićev trg 19, 10000 Zagreb, Croatia; (K.P.); (M.K.); (M.C.); (M.K.R.)
- Department for Packaging, Recycling and Environmental Protection, University North, Trg dr. Žarka Dolinara 1, 48000 Koprivnica, Croatia
| | - Zvonimir Matusinović
- Department for Safety and Protection Engineering, Karlovac University of Applied Sciences, Trg J.J. Strossmayera 9, 47000 Karlovac, Croatia; (S.C.); (H.P.); (Z.M.)
| | - Marijana Kraljić Roković
- Faculty of Chemical Engineering and Technology, University of Zagreb, Marulićev trg 19, 10000 Zagreb, Croatia; (K.P.); (M.K.); (M.C.); (M.K.R.)
| | - Boštjan Genorio
- Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, SI-1000 Ljubljana, Slovenia; (B.G.); (U.L.Š.)
| | - Urška Lavrenčič Štangar
- Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, SI-1000 Ljubljana, Slovenia; (B.G.); (U.L.Š.)
| | - Ana Lončarić Božić
- Faculty of Chemical Engineering and Technology, University of Zagreb, Marulićev trg 19, 10000 Zagreb, Croatia; (K.P.); (M.K.); (M.C.); (M.K.R.)
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Dua R, Sharufa O, Terry J, Dunn W, Khurana I, Vadivel J, Zhang Y, Donahue HJ. Surface modification of Polyether-ether-ketone for enhanced cell response: a chemical etching approach. Front Bioeng Biotechnol 2023; 11:1202499. [PMID: 37744253 PMCID: PMC10517429 DOI: 10.3389/fbioe.2023.1202499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2023] [Accepted: 08/28/2023] [Indexed: 09/26/2023] Open
Abstract
Polyether-ether-ketone (PEEK) is increasingly becoming popular in medicine because of its excellent mechanical strength, dimensional stability, and chemical resistance properties. However, PEEK being bioinert, has weak bone osseointegration properties, limiting its clinical applications. In this study, a porous PEEK structure was developed using a chemical etching method with 98 wt% sulfuric acids and three post-treatments were performed to improve bone cell adhesion and proliferation. Four groups of PEEK samples were prepared for the study: Control (untreated; Group 1); Etched with sulfuric acid and washed with distilled water (Group 2); Etched with sulfuric acid and washed with acetone and distilled water (Group 3); and Etched with sulfuric acid and washed with 4 wt% sodium hydroxide and distilled water (Group 4). Surface characterization of the different groups was evaluated for surface topology, porosity, roughness, and wettability using various techniques, including scanning electron microscopy, profilometer, and goniometer. Further chemical characterization was done using Energy-dispersive X-ray spectroscopy to analyze the elements on the surface of each group. Bone cell studies were conducted using cell toxicity and alkaline phosphatase activity (ALP) assays. The SEM analysis of the different groups revealed porous structures in the treatment groups, while the control group showed a flat topology. There was no statistically significant difference between the pore size within the treated groups. This was further confirmed by the roughness values measured with the profilometer. We found a statistically significant increase in the roughness from 7.22 × 10-3 μm for the control group to the roughness range of 0.1 µm for the treated groups (Groups 2-4). EDX analysis revealed the presence of a 0.1% weight concentration of sodium on the surface of Group 4, while sulfur weight percentage concentration was 1.1%, 0.1%, and 1.4% in groups 2, 3, and 4, respectively, indicating different surface chemistry on the surface due to different post-treatments. Cell toxicity decreased, and ALP activity increased in groups 3 and 4 over 7 days compared with the control group. It is demonstrated that the surface modification of PEEK using a chemical etching method with post-processing with either acetone or sodium hydroxide provides a nano-porous structure with improved properties, leading to enhanced osteoblastic cell differentiation and osteogenic potential.
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Affiliation(s)
- Rupak Dua
- American Dental Association Science and Research Institute (ADASRI), Gaithersburg, MD, United States
- Department of Chemical Engineering, Hampton University, Hampton, VA, United States
| | - Onessa Sharufa
- Department of Chemical Engineering, Hampton University, Hampton, VA, United States
| | - Joi Terry
- Department of Biology, Hampton University, Hampton, VA, United States
| | - William Dunn
- The New Horizons Governor’s School for Science and Technology, Hampton, VA, United States
| | - Indu Khurana
- Department of Economics and Business, Hampden-Sydney College, Hampden-Sydney, VA, United States
| | - Jagasivamani Vadivel
- Department of Chemical Engineering, Hampton University, Hampton, VA, United States
| | - Yue Zhang
- Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, VA, United States
| | - Henry J. Donahue
- Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, VA, United States
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Bussetti G, Menegazzo M, Mitko S, Castiglioni C, Tommasini M, Lucotti A, Magagnin L, Russo V, Li Bassi A, Siena M, Guadagnini A, Grillo S, Del Curto D, Duò L. A Combined Raman Spectroscopy and Atomic Force Microscopy System for In Situ and Real-Time Measures in Electrochemical Cells. MATERIALS (BASEL, SWITZERLAND) 2023; 16:2239. [PMID: 36984119 PMCID: PMC10051831 DOI: 10.3390/ma16062239] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 03/07/2023] [Accepted: 03/08/2023] [Indexed: 06/18/2023]
Abstract
An innovative and versatile set-up for in situ and real time measures in an electrochemical cell is described. An original coupling between micro-Raman spectroscopy and atomic force microscopy enables one to collect data on opaque electrodes. This system allows for the correlation of topographic images with chemical maps during the charge exchange occurring in oxidation/reduction processes. The proposed set-up plays a crucial role when reactions, both reversible and non-reversible, are studied step by step during electrochemical reactions and/or when local chemical analysis is required.
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Affiliation(s)
| | - Marco Menegazzo
- Department of Physics, Politecnico di Milano, 20133 Milan, Italy
| | - Sergei Mitko
- NT-MDT BV, Hoenderparkweg 96 b, 7335 GX Apeldoorn, The Netherlands
| | - Chiara Castiglioni
- Department of Chemistry, Materials and Chemical Engineering, Politecnico di Milano, 20133 Milan, Italy
| | - Matteo Tommasini
- Department of Chemistry, Materials and Chemical Engineering, Politecnico di Milano, 20133 Milan, Italy
| | - Andrea Lucotti
- Department of Chemistry, Materials and Chemical Engineering, Politecnico di Milano, 20133 Milan, Italy
| | - Luca Magagnin
- Department of Chemistry, Materials and Chemical Engineering, Politecnico di Milano, 20133 Milan, Italy
| | - Valeria Russo
- Department of Energy, Politecnico di Milano, 20133 Milan, Italy
| | - Andrea Li Bassi
- Department of Energy, Politecnico di Milano, 20133 Milan, Italy
| | - Martina Siena
- Department of Civil and Environmental Engineering, Politecnico di Milano, 20133 Milan, Italy
| | - Alberto Guadagnini
- Department of Civil and Environmental Engineering, Politecnico di Milano, 20133 Milan, Italy
| | - Samuele Grillo
- Department of Electronics, Information and Bioengineering, Politecnico di Milano, 20133 Milan, Italy
| | - Davide Del Curto
- Department of Architecture and Urban Studies, Politecnico di Milano, 20133 Milan, Italy
| | - Lamberto Duò
- Department of Physics, Politecnico di Milano, 20133 Milan, Italy
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